Short version: obscenity has to do with sex, not violence.
Protected and Unprotected Speech
The First Amendment does not list exceptions for "the freedom of speech." Nevertheless, the Supreme Court has set aside certain kinds of speech as "unprotected" by the First Amendment. When speech is unprotected, state governments are effectively able to restrict it however they see fit. One major category of unprotected speech is obscenity. Here is the key authoritative text, now known as the Miller Test:
"[O]bscene material is unprotected by the First Amendment. 'The First and Fourteenth Amendments have never been treated as absolutes.' We acknowledge, however, the inherent dangers of undertaking to regulate any form of expression. State statutes designed to regulate obscene materials must be carefully limited. As a result, we now confine the permissible scope of such regulation to works which depict or describe sexual conduct. That conduct must be specifically defined by the applicable state law, as written or authoritatively construed. A state offense must also be limited to works which, taken as a whole, appeal to the prurient interest in sex, which portray sexual conduct in a patently offensive way, and which, taken as a whole, do not have serious literary, artistic, political, or scientific value."Notice how obscenity is limited to "works which depict or describe sexual conduct." By definition, violence without sexual conduct can't be classified as legally obscene.
— Miller v. California, 413 U.S. 15 (1973), edited for readability
Variable Obscenity
In 1965, the owner of a Long Island lunch and periodicals business sold porn magazines to a 16 year old boy. New York had a law with wording similar to an earlier version of the Miller Test, with the addition of "for minors," "to minors," etc. The vendor was charged for violating this law and the case eventually made its way to the Supreme Court.
Can something be protected, non-obscene speech for adults and yet be obscene, unprotected speech for minors? The Courted decided: yes, it can!
"We do not regard New York's regulation in defining obscenity on the basis of its appeal to minors under 17 as involving an invasion of such minors' constitutionally protected freedoms. Rather [the New York law] simply adjusts the definition of obscenity 'to social realities by permitting the appeal of this type of material to be assessed in term of the sexual interests' of such minors. That the State has power to make that adjustment seems clear, for we have recognized that even where there is an invasion of protected freedoms 'the power of the state to control the conduct of children reaches beyond the scope of its authority over adults.'"
— Ginsberg v. New York, 390 U.S. 629 (1968), edited for readabilityThis is a BIG DEAL. The Court is saying that New York can classify material that's not obscene for adults as obscene for minors because, in general, states can vary the definition of an unprotected speech category where minors are concerned.
Gov. Schwarzenegger vs. Kratos
In 2005, California passed a bill prohibiting the sale or rental of violent video games to minors, where:
"'Violent video game' means a video game in which the range of options available to a player includes killing, maiming, dismembering, or sexually assaulting an image of a human being, if those acts are depicted in the game in a manner that does either of the following:Section (A) should look familiar. It's similar to the Miller Test adjusted for minors, with two major differences. Part (i) drops the sexual requirement so that it can be applied to violence. Part (iii) completely inverts the serious value check. In the Miller Test, the presence of serious value overrides the other two parts and makes a work non-obscene no matter how offensive it is to a community. In the California law, the presence of offensive elements voids any value in the work. Section (B) puts a ban on additional games, just in case section (A) didn't throw a wide enough net. Altogether, this makes three likely grounds for questioning the law's constitutionality:
(A) Comes within all of the following descriptions:
(i) A reasonable person, considering the game as a whole, would find appeals to a deviant or morbid interest of minors.(B) Enables the player to virtually inflict serious injury upon images of human beings or characters with substantially human characteristics in a manner which is especially heinous, cruel, or depraved in that it involves torture or serious physical abuse to the victim."
(ii) It is patently offensive to prevailing standards in the community as to what is suitable for minors.
(iii) It causes the game, as a whole, to lack serious literary, artistic, political, or scientific value for minors.
— California AB-1179, edited for readability
- Dropping the sexual requirement.
- Inverting the value check.
- Banning games that fall outside the Miller-esque framework.
The Limits of Control
In Ginsberg, the Court had decided that the obscenity exception for free speech rights could come in an adult version and a minor version. California's video game law raised another question:
Can there be free speech exceptions that only come in a minor version?There isn't a free speech exception when it comes to violent content for adults, so (1) a brand new exception would be required and (2) it would only apply to minors. First, the Court pointed at precedent against introducing new free speech exceptions for adults:
"Last Term, in Stevens, we held that new categories of unprotected speech may not be added to the list by a legislature that concludes certain speech is too harmful to be tolerated. Stevens concerned a federal statute purporting to criminalize the creation, sale, or possession of certain depictions of animal cruelty. [...] We held that statute to be an impermissible content-based restriction on speech. There was no American tradition of forbidding the depiction of animal cruelty—though States have long had laws against committing it.
The Government argued in Stevens that lack of a historical warrant did not matter; that it could create new categories of unprotected speech by applying a 'simple balancing test' that weighs the value of a particular category of speech against its social costs and then punishes that category of speech if it fails the test. [...] We emphatically rejected that 'startling and dangerous' proposition.
— Brown v. Entertainment Merchants Association, 564 U.S. 08-1448 (2011)Violence may not be a valid free speech exception for adults, but can't it be an exception that only applies to minors?
"[The California Act] does not adjust the boundaries of an existing category of unprotected speech to ensure that a definition designed for adults is not uncritically applied to children. California does not argue that it is empowered to prohibit selling offensively violent works to adults —and it is wise not to, since that is but a hair’s breadth from the argument rejected in Stevens. Instead, it wishes to create a wholly new category of content-based regulation that is permissible only for speech directed at children.In other words, minors are only subject to the same basic free speech exceptions as adults, though these exceptions may be applied differently to minors. There is no basic free speech exception that has to do with depictions of violence, therefore violent video games are constitutionally protected speech for Americans of all ages.
That is unprecedented and mistaken. '[M]inors are entitled to a significant measure of First Amendment protection, and only in relatively narrow and well-defined circumstances may government bar public dissemination of protected materials to them.' Erznoznik v. Jacksonville [...]. No doubt a State possesses legitimate power to protect children from harm [...], but that does not include a free-floating power to restrict the ideas to which children may be exposed. 'Speech that is neither obscene as to youths nor subject to some other legitimate proscription cannot be suppressed solely to protect the young from ideas or images that a legislative body thinks unsuitable for them.' Erznoznik"
— Brown v. EMA, 564 U.S. 08-1448 (2011)
This applies to books too, if anyone is still reading those things. I do recommend reading the whole majority opinion in Brown v. EMA. It makes excellent points about moral panics, censorship, and violence in children's literature.